January is peak time to visit
Antarctica as the weather is fair and there is nearly 24 hours of daylight. This typically allows for good access to the designated landing sites that you're allowed to visit by Zodiac boat from your ship, to walk amongst penguin colonies and visit historic sites such as expeditioners' huts.
One of the main reasons in January...the penguin chicks are at their fluffiest and cutest! So if baby penguins are what you want to see, January is the best time to visit. You should see plenty of seals about at this time as well as migrating whales; humpbacks start arriving from January and you may also see orca.